Guys, of all the things that I have built in my life I have never built a cattle gap. I have a customer wanting one 20ft wide by 8ft across. They will need to be able to drive a loaded semi truck as well as logging equipment over it. I was thinking of going with 3" sch40 pipe spaced 6" apart with 6" I beam every 4ft under it spanning the 8ft. The I beams will sit down into a concrete footings. What do you think? To heavy/not enough? any advice is recommended. Thanks. ~Jackson

If a cattle gap is the same as a cattle gaurd, then the only thing I can go by is memory and I do not remember the rails being that far apart.
Seems to me there was more like a 1:1 ratio of rail to space.

Hammack welding, here is a site I thought you might like to see, if nothing else, how expensive these things actually are!
I worked at a feedlot when I was in high school and we had a cattle guard like this. Did have a couple of cows in one batch actually walk on the pipes and go over it like they were walking on ice! So, we pulled it up and sleeved a larger pipe over the existing pipes (so they rolled easily) and that kept them in!

Basically how a cattle guard functions is, a way to have a gate to keep cattle in and yet you can come and go at will with a wheeled vehicle. It is a trench or small ditch that is covered with this in a simplistic version a gate laid flat. The reasoning, the cattle won't cross over the pipes, when they try, they fall in the trench scaring them thus they stay on their side of the guard. Needs to be wide enough that the cattle can't jump across. Yet heavy enough that it holds a tractor/loader or truck and trailer. If you use horses, some put a slanted wing so the wing folds down or folds up straight vertical and allows the horse and rider to walk on firm ground. Hope this helps.

I don't have any exact measurements for you, but I bet you are close. Try to get the I beams close to where the trucks will be driving over it. Don't attach the pipes to the frame, build it to where the pipes sit in there loosely, and then if a cow does get her foot in she's not stuck. The pipes can be removed to clean the pit out (big problem with west texas dirt...). Only thing with this design, if the vehicle stops on the guard with the drive axle, it can get stuck as the rails can spin freely, like the truck was parked on a conveyor.

Jackson,
Attached are a few pics of a cattle guard I made. It is a bit different than the normal one in that it has no pit underneath. Instead, the grid is held up by springs and when the vehicle drives over it, the springs stretch and the grid goes to the ground. Mine is only about half as big as the one you are working on, 7 1/2' x 11 1/2', but it might give you some ideas. I spaced the 2" heavy wall square tubing with a 3" space between the bars. I coped 45's out with an iron worker on the angle iron running across the top to act as a spacer and as a stablilizer. Underneath is 3/8 x 6" flat steel to beef up the whole thing. I have this one installed over a pit but that is because the old cattle guard wore out and it had a pit.
I drive tractors, semi's hauling feed etc over this all the time. I should fill in the pit under it so the grid has a more stable base to rest against when there is a load on it.
"Most of the time" the cattle will step on it and the whole thing moves so they back off. I do have one bull that very carefully will walk across it to get into the yard. durn him anyway.

You want to keep your bars spaced wided enough (3-4in.) so that if a cow sticks her foot into it, she can get it pulled back out, but not so wide that she is comfortable stepping down into the pit once the dirt starts filling in. You dont want it spaced too far apart or it'll be rough to cross it too.
Good luck,
OleDog

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